1. Field of the Invention
The present invention relates to a multimedia streaming system and method, and more particularly, to a real-time multimedia streaming system and method, in which a transfer bit rate is adaptively controlled according to the state of a network by comparing an interval between packets that are transmitted from a server to a client network with an interval between packets that are received by a server from a client network.
2. Description of the Related Art
A bit rate of data to be transmitted is referred to as a data transfer rate (or data rate). The bandwidth of a path through which data are transmitted, or a path through which data are streamed (hereinafter, referred to as a ‘streaming path’) is a very important factor for real-time multimedia streaming in an Internet network.
For example, in case that there is no bottleneck on the streaming path or there is no network congestion, it is preferable that a bit rate of data that are transmitted by a streaming server (hereinafter, referred to as a ‘transfer bit rate’), and a bit rate of data that are received from the client (hereinafter, referred to as a ‘receiving bit rate’) are the same. Thus, data that are resolved into packets by the streaming server and are transmitted to the client through the streaming path may be decoded and regenerated in real-time by the client without any delay or loss. However, in case that the transfer bit rate is larger than the bandwidth of the streaming path, the data that are transmitted from the streaming server to the client may be lost in a router which causes the bottleneck.
That is, when network congestion or bottleneck on the streaming path occurs, the receiving bit rate of the client, which receives the packets that are transmitted by the streaming server, is gradually decreased, and thus, the packets cannot be received and are lost.
For example, in a streaming method and apparatus disclosed in U.S. Pat. No. 5,768,527, a bit rate is changed only on the basis of packet loss. Accordingly, it is difficult to immediately meet the variation of the state of a network, and it takes much time to normally transmit packets.